Compression-sealing "plug-in" doors are commonly provided for railway freight cars where an ambient sealing of the interior is desired, a typical case in point being refrigerated railway cars. Such doors often have a gear-operated door frame engaging mechanism coupled to be driven by rotation of a handle affixed to a drive shaft which operates the mechanism to alternatively sealingly close the door, or alternatively to unlock it. These mechanisms are inherently powerful, and when the door is compressingly sealed, a significant reverse torque is imparted to the handle as a result of the compression forces. Such a reverse torque can also arise from a number of other factors, such as a shifted load of product inside the car leaning against the door, or the force of the door's own weight when the car is tilted to lean outward. Handles are routinely secured against counter-rotation in the door-opening direction by handle locking mechanisms of one sort or another. To open the door, however, the handle lock must be released. If, at that time, or at any other time during rotation of the handle in the door-opening direction, the operator should lose control of the handle, the handle will frequently spin, resulting in a highly dangerous condition to the operator, and occasionally resulting in broken bones.
Anti-spin devices are now becoming known which will automatically arrest such dangerous spinning, and which can readily be incorporated into the interior of the railway car door at the time of manufacture, or which may alternatively be retro-fitted by partial disassembly of the door to give access to the existing mechanism to permit installation. Because of the high number of railway cars already in use, a less expensive retro-fit system for gear-operated doors would be economically advantageous.